Abstract: In one example, a heatable centre wall for a beehive is provided for the hyperthermal reduction of varroa and/or for heating honeycombs for maximizing the harvest yields. The centre wall includes a continuous PTC (positive temperature coefficient) heating foil having a non-linear PTC (positive temperature coefficient) effect. As well, the PTC (positive temperature coefficient) heating foil has on at least one of its sides a layer having a comb pattern.

Abstract: Thin walled components, which are moving or capable of movement, are stopped or clamped by the cooperation between an electromagnet core and an independent short-circuit component. The mobile component is always in contact with the core of the electromagnet and with the short-circuit component such that no noise is produced when the mobile component is stopped or clamped.

Abstract: The invention relates generally to the processing of a data medium, in which an additional sound sequence is recorded or mixed in gaps between sections occupied by an original recording which is to remain on the data medium.

Abstract: The invention relates to a tape handling device associated with a picture-taking (recording) or reproducing (replay) device having a drive motor, a transmission gear to be actuated by the motor, a reversing device for reversing the sense of rotation of the drive consisting of the motor and gear train, and a control device likewise actuated by the motor.

Abstract: A camera having a forward lens unit including a displaceable lens for providing a variable focal length, a film plane, a base objective having a fixed focal length, and an aperture diaphragm between the displaceable lens and the film plane together with automatic drive means for displacing the base objective axially in direct proportion to the diaphragm stop of the aperture diaphragm to thereby shift the image plane defined by the forward lens unit and the base objective and provide a substantially constant circle of diffusion at the film plane.

Abstract: An electronic switching system for the control of a load, such as a motor serving to adjust the diaphragm of a motion-picture camera, comprises a normally inactive comparison circuit including a transistor bridge with a pair of NPN transistors in one pair of adjoining arms and a pair of PNP transistors in the other pair. Two complementary transistors in each half of the bridge, lying between diagonally opposite corners, are provided with a common biasing circuit shunted across that bridge diagonal, the load being connected across the other bridge diagonal. Each biasing circuit includes a resistive voltage divider with taps joined to the bases of the associated bridge transistors and a group of cascaded ancillary transistors connected across a section of the voltage divider containing one of these taps. The first ancillary transistor of each cascaded group has its base connected to an associated input terminal receiving a switching signal and a reference voltage, respectively.

Abstract: The operating condition of a producer of intermittent radiation, such as a motion-picture projector or a television receiver, is monitored by a detector circuit including a photoelectric transducer followed by a filter with a pass band centered on the interruption frequency. The detector output is used to control the lighting of a lamp or the drawing of a curtain in a room where ambient illumination is to be suppressed or reduced during operation of the monitored apparatus. In one embodiment, the band-pass filter is inserted in a negative-feedback loop which suppresses the frequencies falling within its pass band. A band-stop filter may be connected in cascade with the band-pass filter to block the passage of signals due to other radiation such as ambient artificial light.